215 patients undergoing elective CTU due to macroscopic hematuria were administered either 5, 2.5, or 0 mg furosemide. The control group of 15 patients given 0 mg was considered too small to draw any conclusions. The results were focused on bladder volume, bladder distension, and attenuation of bladder content in CMP and EP. The effect of furosemide comes approximately 10 minutes after administration according to the manufacturer, hence should only affect the results in EP. 5 mg provided a larger average bladder volume in EP with 370±224 ml (28-1052), compared to 274±120 ml (43-628) after 2.5 mg (p<0.001). Satisfactory distension was defined as primarily convex bladder walls in both axial and coronary planes. The ratio was 85% after 5 mg and 80% after 2.5 mg. To reduce the risk of hiding tumors by the contrast blooming effect,5 a low difference of attenuation between contrast-enhanced urine and bladder tumors (which is around 57 HU in EP)6 is desirable. The closest attenuation was reached after 5 mg with 266±89 HU (103-524), compared to 362±156 HU (118-948) after 2.5 mg (p<0.001).
In conclusion, 5 mg furosemide is preferred rather than 2.5 mg since the higher dose resulted in larger bladder volume and a more suitable attenuation of the bladder content. There was no difference between the doses concerning rate of satisfactory bladder distension. However, to find the most optimal furosemide dose, both the quality of bladder filling and patients’ experiences are important. Further research assessing patients’ experiences with these furosemide doses is welcome.
Written by: Adina Ljungberg,1 Monica Segelsjö,1 Pär Dahlman,1 Malin Helenius,1 Mats Magnusson,2 Anders Magnusson1
- Uppsala University Section of Radiology, Department of Surgical Sciences, Uppsala Sweden.
- Pharmetheus AB, Uppsala Sweden
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- Uppsala University Hospital. Metodbok CT urinvägar, hematuri [Book of Procedure of CT urinary tracts, hematuria], version 0.9. 2017.
- Pettersson H. The Nicer Global Textbook of Radiology II Chest, Abdomen, Urogenital system, Tropical disease. Lund Sweden: The NICER institute, 1995:1126.
- Helenius M, Segelsjö M, Dahlman P, et al. Comparison of four different preparation protocols to achieve bladder distension in patients with gross haematuria undergoing CT urography. Radiography 2012;18:206-211.
- Grimes J, Duan X, Yu L, et al. The influence of focal spot blooming on high-contrast spatial resolution in CT imaging. Med Phys 2015;42:6011-6020.
- Helenius M, Dahlman P, Magnusson M, et al. Contrast enhancement in bladder tumors examined with CT urography using traditional scan phases. Acta Radiol 2014;55:1129-1136.